Fetal Echocardiography

Overview

Congenital heart disease (CHD) is a frequent birth defect. Advances in prenatal cardiac anomaly detection have resulted in a considerable reduction in newborn morbidity and death. With early diagnosis, a baby with a cardiac anomaly can receive good intranatal and postnatal care, and the family can be emotionally and financially prepared to accept such a baby.

Fetal echocardiography is a type of ultrasound test. The four-chamber view and the outflow-tract view are utilized in prenatal echocardiography to identify heart abnormalities. The most essential goal of a targeted anomaly scan is to identify patients that require a fetal echocardiography.

It is necessary to identify any associated truncal and chromosomal abnormalities. This exam allows your doctor to view the anatomy and function of your unborn child's heart in more detail. It is usually performed between weeks 18 and 24 of the second trimester.

The test employs sound waves that "echo" off the cardiac structures of the fetus. These sound waves are analyzed by a machine, which produces an image of the inside of the heart, known as an echocardiogram. This picture shows how your baby's heart developed and if it is functioning properly.

Incidence of Congenital Heart Disease(CHD)

CHD affects 8 out of every 1000 live births. However, the fetal population has a substantially greater incidence. Many fetuses with complicated cardiac defects die in the first trimester, even before the cardiac aberration is discovered; some parents choose to terminate the pregnancy after the diagnosis is made in the mid-trimester; and some cardiac malformations are progressive and result in intrauterine mortality.

Cardiac anomalies are known to cluster in families; the risk of having a child with a cardiac anomaly is as follows:

• If a previous child was born with a CHD, the probability of a subsequent child being born with a CHD is 1:20 to 1:100.
• If two previous children were born with CHD, the risk is 1:10 to 1:20.
• If the mother has CHD, the risk is as high as 1:5 to 1:20
• If the father has CHD, the risk is 1:30

When Is Fetal Echocardiography Used?

A fetal echocardiography is not required for all pregnant women. A routine ultrasound will reveal the development of all four chambers of their baby's heart for the majority of mothers.

If prior tests were inconclusive or revealed an irregular heartbeat in the fetus, your doctor may advise you to have this procedure performed.

Healthcare providers recommend fetal echo in these cases:

• Another baby was born with a congenital cardiac condition.
• There is a family history of hereditary cardiac issues.
• A genetic abnormality has been discovered in the fetus.
• You are taking medications that have the potential to cause congenital cardiac abnormalities. Certain medications for seizures, depression, and acne fall under this category. Nonsteroidal anti-inflammatory drugs (NSAIDs) and blood pressure medications are also included (ACE-inhibitors).
• During your pregnancy, you overused alcohol or drugs.
• You have a medical condition such as diabetes, lupus, or phenylketonuria.
• During your pregnancy, you suffered a number of infections. German measles (rubella) and CMV are two examples.
• Other testing yielded abnormal results for you.
• During the exam, your baby's heart rhythms were found to be too rapid, too slow, or irregular.

If you have risk factors such as a family history of heart problems, fetal echoes are often done in the second trimester of pregnancy. This is at about 18 to 24 weeks.

Timing of Fetal Echocardiography

When USG is performed, the fetal heart can be assessed at any moment during the gestation period. Although cardiac features may not be effectively elicited in the first trimester (11–14 weeks), the existence of a pulsatile ductus venosus or tricuspid regurgitation might be a very powerful marker for cardiac and chromosomal disorders.

The fetal heart may be assessed throughout the third trimester, however there are several restrictions due to oligoamnios and shadowing from the fetal spine, ribs, and limbs. The ideal period to assess the fetal heart is during weeks 18–24 of pregnancy.

Equipment Used in The Procedure

The equipment used for fetal echocardiography must have an excellent B-mode and a good cine-loop facility so that the frame of interest may be captured by scrolling back frame by frame. The geographical and temporal resolution must be adequate. Color Doppler, pulsed Doppler, and continuous wave Doppler should all be included in the system. STIC, tissue Doppler, and multiplanar imaging are all additional benefits.

A particular pre-set with a high frame rate, low persistence, and higher compression is required for fetal heart assessment. The system should be able to zoom in on a picture without deteriorating image quality. Color Doppler in the fetus requires a greater pulse repetition frequency (PRF) than the parameters used for standard obstetric color Doppler.

Is There Any Preparation Needed For The Test?

A full bladder is not required for a fetal echocardiography, unlike other standard prenatal ultrasounds. When you come in for your fetal echocardiography, make sure you have as much information as possible, including why you were recommended by your obstetrician or perinatologist. If the reason for the referral is that you have a cardiac defect, providing whatever medical records you have will be extremely useful. The investigation can take anywhere from 30 minutes to more than 2 hours, depending on the findings; if you have additional young children with you, it is always a good idea to bring another care giver.

What Happens During The Exam?

This test is comparable to a standard prenatal ultrasound. An abdominal echocardiogram is a type of echocardiography that is done via your abdomen. Transvaginal echocardiography is what it's called when it's done through your vagina.

Abdominal echocardiography:

An ultrasound is comparable to an abdominal echocardiogram. An ultrasound technician will ask you to lie down and expose your stomach first. They will next apply a lubricating lotion to your skin. The jelly reduces friction, allowing the technician to slide an ultrasound transducer, which sends and receives sound waves, across your skin. The jelly also aids in the transmission of sound waves.

High-frequency sound waves are sent through your body via the transducer. When the waves contact a dense object, such as your unborn child's heart, they reverberate. These echoes are then returned to a computer. The sound waves are too high-pitched to be heard by the human ear.

The technician will move the transducer around your belly to obtain photos of various areas of your baby's heart. Following the procedure, the jelly is removed from your abdomen. You can then resume your daily activities.

Transvaginal echocardiography:

You will be asked to undress from the waist down and lay on an exam table for a transvaginal echocardiogram. A tiny probe will be inserted into your vagina by a technician. The probe creates a picture of your baby's heart using sound waves.

Typically, transvaginal echocardiography is employed in the early stages of pregnancy. It might offer a more detailed view of the fetal heart.

Common anomalies seen on the fetal echocardiography

1. A two-chambered heart: It is a septation defect. The septum, which separates the basic heart into left and right sides, does not form. There is just one atrium, one ventricle, and one AV valve. This abnormality is frequently accompanied with a single outflow tract known as the truncus. Chromosomal abnormalities are known to be linked to.
2. Hypoplastic left heart: Mitral atresia is frequently related with this. During the cardiac cycle, the mitral valve is echogenic and does not move. The left ventricle does not grow normally because there is no flow through the mitral valve. The left ventricle is tiny, echogenic, and lacks color flow. The aortic arch indicates flow reversal, i.e. from the descending aorta into the arch and subsequently into the ascending aorta. From the ductus, the arch of the aorta fills retrogradely.
3. Ebstein's anomaly: This is a chronic condition that worsens with time. The right atrium is significantly expanded. The tricuspid valve is positioned more apically than typical. The offset between the mitral and tricuspid valves is usually approximately 8 mm. On color Doppler, there is regurgitation over the tricuspid valve.
4. Ventricular septal defects: The defect in the ventricular septum has bright margins. There is no flow across the VSD in fetal life because there is no pressure difference between the right and left side of the fetal heart. If the VSD is large, there might be free mixing of blood across the defect.
5. Atrioventricular septal defect: This can be a minor defect such as a membranous VSD or a septum primum atrial septal defect (ASD); a missing crux (also known as an endocardial cushion defect); or a single atrioventricular valve. The endocardial cushion is the developmental genesis of all of these structures. This impairment is frequently linked to chromosomal abnormalities such as trisomy 21 and single-gene disorders such as Ellis-van Creveld syndrome.
6. Tetralogy of Fallot: Septoaortic continuity has been lost. The aorta may be seen crossing over the interventricular septum. On color Doppler, there is turbulence near the aortic root.
7. Transposition of the great arteries: Both the outflows are parallel to each other at the origin. They show similar color flows, indicating that the direction of flow in both the great vessels is the same.
8. Pulmonary stenosis: The pulmonary artery is either exceedingly thin or has poststenotic dilatation. The pulmonary valve is not observed to open sufficiently on real-time echocardiography. Aliasing may be detected on color Doppler. The major pulmonary artery has very high velocities, exceeding 180 cm/s on pulsed Doppler.
9. Rhythm abnormalities of the heart: Rhythm abnormalities are usually detected by the doctor. The radiologist must first rule out any structural abnormalities. The heart's rhythm can then be assessed using M-mode and pulsed Doppler.

The fetal heart rate ranges between 120 and 160 beats per minute (BPM). A rate of less than 120 beats per minute is referred to as bradycardia, while a rate of more than 200 beats per minute is referred to as tachycardia. When the fetal heart pulse is initially seen at around 5 weeks of gestation, it may be around 90 BPM, but it quickly picks up. Premature atrial contraction followed by a compensatory pause is the most frequent rhythm irregularity found in practice. Heart blockages of varied severity may be observed. One area where fetal treatment has had an impact is supraventricular tachycardia; maternal digitalization can restore this arrhythmia to normal.

Risks of a Fetal Echocardiograms

Both the mother and the baby are unharmed by fetal echocardiograms. There are no substantial dangers associated with this type of ultrasonography. However, failing to complete a suggested test may put your kid at danger after birth.

When will I get answers?

The answers accessible will be determined by the setting of the fetal echocardiography, the fetus' gestational age, diagnosis, and the quality of the images. If the investigation is being carried out by a pediatric cardiologist, the pediatric cardiologist will meet with you as soon as the study is over and will give you with a full explanation of the results. If a perinatologist finds a cardiac problem during your initial examination, you will be sent to a pediatric cardiologist for a more extensive diagnosis and counseling.

If the test results are normal, you may be discharged or asked to undergo a repeat test before or after birth, depending on the cause for the test in the first place. Some issues, such as maternal lupus, need many investigations, even if the first one is normal. There may also be a structure that is not visible as clearly as the doctor would like, and you may be asked to return even though there is little indication of a problem.

Even if the study is completely normal and of great quality, you will be advised that not all cardiac disorders can be ruled out. This is due to the fact that circulation in the pregnancy differs from that after delivery. Furthermore, even small holes between the lower chambers of the heart are difficult to see. However, considering the normal fetal circulation, you doctor can provide fairly definitive good news in the case of a normal fetal echocardiogram.

Fetal echocardiograms may be performed consistently after 17–18 weeks of gestation; however, modern technologies, such as endovaginal transducers, can acquire pictures of the heart as early as 12 weeks. If you are scanned before 18 weeks, you will most likely be requested to return for more definite images to confirm the findings of the preliminary investigation. In certain circumstances, 18 weeks is still considered too early.

When a cardiac problem is discovered, the pediatric cardiologist will discuss the diagnosis and consequences in detail as soon as the investigation is finished. After the sonographer has completed the initial study, the doctor may take additional photographs in most circumstances. The pediatric cardiologist will most likely offer and draw diagrams to describe the severity of the heart problem, such as whether it would harm the fetus prior to birth, require immediate transfer after delivery, or require heart surgery after birth.

In almost all cases, you will be asked to return for more fetal echocardiograms as you prepare for birth. Your pediatric cardiologist will provide you with as much information as possible while also informing you of any remaining questions. You may need to see a cardiac surgeon or interventional cardiologist in the future to learn more about heart surgery or other procedures after delivery.

What Happens After Fetal Echocardiography?

Your healthcare provider will look at the results. He or she may order more tests or procedures. They may include:

• Treatment: This may be medicine or procedures to treat fetal heart problems.
• Assessments of fetal wellbeing: You may be asked to count fetal movements to assess overall fetal health.
• Non-stress examination: This monitors the fetal heart rate and movement.
• Profile biophysical (BPP): This is an ultrasound test to examine the general health of the fetus. It measures your heart rate, respiration, movement, muscle tone, and the quantity of amniotic fluid in your womb.
• Echocardiography or ultrasounds: These are tests that are performed to confirm the diagnosis. They also monitor fetal development, look for abnormalities in the fetal heart, and look for other concerns.
• Amniocentesis: This test can detect chromosomal and genetic abnormalities, as well as some birth problems. A needle is inserted through the abdominal and uterine walls and into the amniotic sac by the healthcare professional. He or she collects an amniotic fluid sample.
• Genetic counselling: Based on the heart diagnosis and other findings in the fetus, geneticists and genetic counselors estimate the possibility of a genetic condition and probable problems in other organs. The geneticist can teach patients and their families about the effects of a problem, the likelihood of having or transmitting it, and how it may be avoided, treated, and managed.

Conclusion

Fetal echocardiogram (echo) utilizes sound waves to examine your growing baby's heart. A fetal echocardiogram can aid in the detection of cardiac abnormalities before birth.

The earlier a cardiac condition is identified, the more likely therapy will be effective. This is due to the fact that:

• In certain situations, healthcare practitioners may be able to correct the condition before to delivery.
• Healthcare practitioners may prepare for potential issues that may arise during labor and delivery.
• An early delivery is probable.

Fetal echo has no dangers for either the fetus or the mother. The ultrasound settings are kept as low as feasible. Once the baby is born, treatment may be done. This might be medicine or surgery.